1. Field of the Invention
The present invention is related to an electroplating apparatus for electroplating perforated printed circuit boards during horizontal movement, and in particular to such an apparatus having vertical flow components of the electrolyte solution.
2. Description of Related Art
DE-A-32 36 545 discloses an electroplating apparatus for printed circuit boards, wherein the printed circuit boards are fed horizontally through an electrolyte bath. Driven contacting wheels arranged at one side in the bath feed the printed circuit boards (workpieces) and simultaneously assume the cathodic contacting of the workpieces. A special glide gripping is arranged in the bath at the side opposite the contacting wheels to guide and hold the workpieces. Anodes in the electrolyte bath are soluble anode rods aligned transversely relative to a throughput path and arranged above and below the throughput path.
In another embodiment of DE-A-32 36 545, the upper and lower anodes can be formed by titanium baskets containing the soluble anode material in ball form. Blast connections to which the electrolyte solution is supplied from a reservoir by a plurality of immersion pumps are arranged in the collecting tank of the electroplating means above and below the throughput path. The blast connections are aligned in the throughput direction. The high flow rate of the electrolyte solution through the blast connections refills the bath zone to the desired level and also mixes the electrolyte solution well, ensuring a uniform composition and a uniform current density of the electrolyte solution. For producing even greater turbulence in the bath, the blast connections can be moved back and forth horizontally or in the throughput direction.
EP-A-0 254 962 discloses another electroplating apparatus for treating printed circuit boards during horizontal movement, wherein forceps-shaped contact clamps are provided as conveyor and contacting elements. The contact clamps are arranged on an endlessly circulating drive and clamp the lateral edges of the printed circuit boards.
EP-B-0 276 725 also discloses an electroplating means for treating perforated printed circuit boards during horizontal motion. Electrolyte collectors having openings for the intake and/or outflow of the electrolyte solution, which is directed between the throughput path and the upper or lower anode, are arranged above and below the throughput path and are aligned transversely relative to the throughput path at both the admission side and the discharge side. The arrangement of the electrolyte collectors produces longitudinal flow components in the electrolyte liquid. Flow nozzles aligned transversely relative to the throughput direction produce vertical flow components of the electrolyte solution. These vertical flow components are significant for producing through-contactings in the perforated printed circuit boards.
The current technology in the electroplating of printed circuit boards does not produce optimum quality and distribution of layer thicknesses of the deposited metal layers.